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Thread: Stock tune LTFTs pegged at +25

  1. #1

    Stock tune LTFTs pegged at +25

    What could cause this? Only code is for lean condition. TIA

  2. #2
    Advanced Tuner
    Join Date
    Jul 2004
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    Detroit, MI
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    Re:  Stock tune LTFTs pegged at +25

    Look for exhaust and/or intake leak. I had an exhaust leak that was letting fresh air in just before the O2 sensor. It was thinking that that bank was lean and adding lots of fuel.

    -Matt
    1970 Corvette LS1/T56
    2001 Corvette Z06

  3. #3

    Re: Stock tune LTFTs pegged at +25

    Quote Originally Posted by Scooter70
    Look for exhaust and/or intake leak. I had an exhaust leak that was letting fresh air in just before the O2 sensor. It was thinking that that bank was lean and adding lots of fuel.

    -Matt

    The cats were just replaced on this car by the dealer under warranty. The intake has never been off the car. You'd think that it would take a large exhaust leak to make the LTFTs maxed out. So large that you'd think we could hear it. ;D

  4. #4
    Senior Tuner
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    Nov 2002
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    Re:  Stock tune LTFTs pegged at +25

    Did you do anything naughty to the MAF itself?

  5. #5
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    Re: Stock tune LTFTs pegged at +25

    Quote Originally Posted by jimmyblue
    Did you do anything naughty to the MAF itself?
    LOL! ;D
    1998 Camaro Z28 M6: SLP Lid, Adj. Panhard, SFCs, CAGS!, Hotcam, Hooker Shorties, Katech Tensioner, Catback with Dynomax 17221 3\" Muffler, Mobil-1, Bosch +4s, 160 Stat, !EGR, !MAFless, !FRA, S3 TB

  6. #6

    Re:  Stock tune LTFTs pegged at +25

    One car has a GMAF and the other has an SLP MAF. ;D

  7. #7
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    Prince George, BC
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    Re:  Stock tune LTFTs pegged at +25

    you did test your fuel pressure and most importantly the fuel volume delivered? Lately a lot of fuel pumps have been dying due to plugged up strainers. To test for this run your tank down to 3/8 tank or so, then take the pressure line off your fuel filter and run it into a container (keep cranking for at least 15 seconds) or preferable jumper the fuel pump prime connector. Fuel flow should be very steady, if at all sporadic or full of air bubbles suspect a plugging strainer, You can use any ethanol based injector cleaner to try clean up the sock. My best results were with the Gm port injector cleaner (two bottles in one tank full) and high quality fuel.
    There is no replacement for displacement?&&sure there is, its called a Blower!

  8. #8

    Re: Stock tune LTFTs pegged at +25

    I haven't checked fuel on either car. One of them (SLP MAF) seems to have worked out whatever was wrong. The other car is the one which just had the cats replaced. Could this be a result of poor workmanship at the dealer?